What PDF Compare helps you do

Compare two PDFs page by page with a side-by-side visual preview. It is the quickest way to check a revised document against the original without flipping between two windows. The comparison is visual, not a text diff, so it shows how pages look rather than which words changed.

Both PDFs are compared in your browser. Neither file is uploaded to Haivix.

How it works

A PDF stores positioned drawing instructions rather than flowing paragraphs, which is why editing one is different from editing a document. Page content, fonts, images and annotations are separate objects, and a page only carries a text layer if the producer wrote one. Most tools here rebuild or render the file in your browser with pdf-lib and pdf.js; the formats that need a full office engine, such as Word, Excel, PowerPoint, PDF/A and HTML, use the Haivix service and say so in their privacy note. Every tool writes a new file and leaves the original untouched. Because content is placed by coordinates, extraction often returns text runs in visual order rather than sentences, and columns or tables can arrive interleaved.

How to use PDF Compare

Load the original PDF as PDF A.
Load the revised PDF as PDF B.
Read the page pairs side by side.
Inspect the pages where the rendered content differs.

When to use it

Confirm exactly what changed between two versions of a contract.
Check a re-export against the previous file.
Catch unintended differences after an edit.
Compare a proof with the final artwork.
Check that a print export matches the screen version.
Spot a missing page after a merge.

When not to use it

Do not expect a word-level diff; this is a visual comparison.
Do not use it on two files with different pagination and expect aligned content.
Do not treat identical rendering as proof that the underlying text is identical.

Example

Two versions of a report with one changed sentence on page three look different in the third pair while the rest appear the same. If one file has an extra page at the start, every following pair is offset and the comparison becomes misleading. A reflowed document can look different on many pages even when little text changed.

What you can do with PDF Compare

Load two PDFs at once.
Render corresponding pages side by side.
Compare the same page number in both files.
Show page counts for each document.
Highlight differences by visual inspection.
Keep both files in the browser.

Example: work on a copy and check the output

Keep the original file. These tools produce a download rather than editing in place, so a failed operation never damages the source.

Check whether the PDF has a real text layer before relying on extraction. A scan is an image, so text tools return little or nothing until OCR has run.

Unlock encrypted files first. A password-protected PDF cannot be reordered, cropped or annotated until it has been opened with the correct password.

Review the output before sending it on. Fonts can substitute, overlays do not always remove what is underneath, and page boxes can shift content near the edges.

Note the page size and orientation before laying anything out. A mixed document can contain portrait and landscape pages, and a tool that assumes one size may crop or offset the others.

Keep a note of the operation and its settings. If a recipient questions the result, reproducing it from the original is faster than guessing which options were used.

What to know before you start

Comparison is page-based and sensitive to reflow, so a shift in content can flag many pages.
Image-only PDFs compare as images and may not expose text-level differences.
There is no automatic diff score, change list or export of findings.
Page alignment assumes both files start at the same logical page.

Common mistakes

Comparing documents with different page counts and assuming pages align.
Expecting highlighted changes rather than a visual pair.
Ignoring image resolution differences that make pages look unlike without content changes.
Closing one file before the other has finished rendering.

Troubleshooting

If the previews are blank, one file may still be loading or may be malformed.

If pages look offset, the documents have different page counts or start pages.

If a page looks different but the text matches, fonts or images may have changed.

If only the first page shows, wait for the renderer to finish.

PDF Compare